The Great Spring Sickness was a plague epidemic which took place in 209 AC and 210 AC, killing tens of thousands in the Seven Kingdoms. Victims are said to have "died in the spring".[1]

History

The plague killed tens of thousands in the Seven Kingdoms with the major cities affected the most; it was bad in Lannisport, worse in Oldtown, but worst of all in King's Landing, where four in ten succumbed to it. A strong man could wake up healthy in the morning and die by the evening, so swiftly did the plague strike.[2]

Dorne and the Vale of Arryn did not suffer from the Great Spring Sickness, as they closed off their access roads and their ports to all travellers.[2] Ser Duncan the Tall and his squire, Prince Aegon Targaryen, were in Dorne for the duration of the plague so were unaffected by it.[2]